The use of diaphragm pumps for spray painting and other applications is, of course, well known. Such applications tend to be fairly low in pressure. Such pumps, when operated by an electrical motor, typically have a pressure sensor which provides a signal to stop and start the motor so as to maintain the desired pressure. In known units, the pressure utilizes a diaphragm which is located at the end of an elongated tube. Typically this tube is located so as to connect with an outlet passage from the pump. While such an arrangement is capable of providing workable operation, much care must be taken to properly flush and clean the unit after use. If such care is not taken, the paint or similar material may dry in the tube adjacent the sensor such that when the unit is again operated the sensor would not properly read the pressure actually being produced by the unit. The tube in which the sensor is located, in effect, produces a condition of little or not actual flow such that the clogging easily takes place.
Also, in diaphragm pumps, the connecting rod is attached to the central area of the diaphragm and no support is provided to the flexing portion of the diaphragm, except where it is clamped at its peripheral edge. When such prior art units are operated at relatively elevated pressures (such as 300 psi) the diaphragm is quite prone to failure.